Solenopsis

is a speciose myrmicine genus with a worldwide distribution. The group is best known for some of its larger members, the fire ants, but most of the diversity in Solenopsis is found in small subterranean species. Several species of fire ants- most notably Solenopsis invicta- have become economically important pests where introduced by human commerce.

Solenopsis phoretica & Pheidole dentata

Among the oddest of all ants is the tiny Solenopsis phoretica, a presumably parasitic species whose females ride piggyback on Pheidole queens. Nearly nothing is known about its biology, having only been collected twice. Austin, Texas, USA.